libftdi Archives

Subject: Re: write/read syncronization

From: Uwe Bonnes <bon@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Thu, 4 Feb 2010 13:58:25 +0100
>>>>> "Igor" == Igor Nikitin <igor.nikitin@xxxxxxxxxxx> writes:

    Igor> The question is how to force the immediate reply to have

Try to understand USB packets and how the FT stuffs these packets and the FT

The FT fill up a buffer and sends it out when its full  or when the latency
elapses. Set the latency low and sleep shortly between the 
ftdi_write_data() and ftdi_read_data()

    Igor> The other question is why does the very first message disappear?
    Igor> Restarting test program again and again, I see that the first
    Igor> "one" is almost always missed, not appearing in further output.

I don't know. Maybe the uC is not out of reset? Maybe the FT takes some time
to setup?  What happens if you loopback tx/rx at the FT232 without the uC
    Igor> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    Igor> "";>

Please, no HTML in mail.

Uwe Bonnes                bon@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------

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